ArrayStuff.java

import java.io.*;
import java.util.*;

public class ArrayStuff {

    private int[] a;
    private Random r = new Random();

    public ArrayStuff() {
        a = new int[20];
        for (int i=0;i<a.length;i++) 
            a[i] = r.nextInt(100);
    }

    public String toString() {
        return Arrays.toString(a);
    }

    public int get(int n) {
        return a[n];
    }

    public int findMaxIndex() {
        int maxi = 0;
        for (int i=0 ; i<a.length; i++) {
            if (a[i] > a[maxi]) 
                maxi = i;
        }
        return maxi;
    }

    public int find(int n) {
        for (int i=0; i<a.length; i++) {
            if (a[i] == n)
                return i;
        }
        return -1;
    }

    public double mean() {
        double sum = 0;
        for (int i=0; i<a.length; i++) {
            sum += a[i];
        }
        return sum / a.length;
    }
    
    public double stddev() {
        double  mean = mean();
        double sumMeans = 0;
        for (int i=0; i<a.length; i++) {
            sumMeans += Math.pow(a[i] - mean, 2);
        }
        return Math.sqrt(sumMeans / a.length);
    }
}